SPATIAL CONSIDERATIONS Tim Oxley & Helen ApSimon UK National Focal Centre for Integrated Assessment Imperial College London

AIM: Compatibility national scale (UKIAM) and European scale RAINS-> nesting Some issues target setting/gap closure MTFR/CLE primary PM

Different approaches to target setting ? Dependence on critical loads of new approach? NB Base year data and critical loads are verifiable Need to examine assumptions in modelling CLE and MTFR & using for target setting carefully.

deposition Case 1Case 2 Base year CLE 2020 Critical load MTFR New IIASA targets Old gap closure

S-R matrix for combined sources each country Change in national emissions Change in conc./deposition RAINS Distinguish change in emission for different sources S-R matrix & abatement cost :- Source 1 Source 2… etc UKIAM

MAP SHOWS % REDUCTION IN REDUCED NITROGEN DEP AT MTFR FOR NH 3. NB Different types of farming in different areas  spatially varying applicability of measures  Local cost curves in UKIAM

due to UK sources PM 2.5 Advantages combining primary and secondary- but primary very different characteristics and source dependence Aim to reduce health risks of population-> population weighted concentrations

Local, mid and far range contributions to population exposure from primary PM sources Not only important how much emissions are cut but also WHICH emissions

EMEP estimates- source apportionment for PM2.5 concs-> some countries ~50% imported For population exposure, correlation between urban populations and urban enhancement increases role of national sources. e.g. country of 15 M people with average background due to own sources of 0.5  g/m3, and same 0.5  g/m3 from imported sources PLUS 4 M people in urban concns enhanced by 3  g/m3 Imported contribn = 7.5 National contribn = = 19.5 ~ 72% of total NB Also imported contribn. Is mainly from neighbouring countries and seas ? EMEP overestimate because artificial attribution for grid-squares across borders

CONCLUSION As well as emission ceilings for primary PM 2.5 need to ensure effective reduction in “population exposure” ( including own and neighbouring countries where relevant). ? Ancillary targets ?role of ships in ports Also need to consider target setting overall very carefully- e.g. relation to critical loads, CLE and MTFR.